Antarctica is a very harsh and extreme
environment though is very rich in wildlife due to the very
high productivity of the Antarctic Ocean during the summer
months driven by long days providing abundant light and
copious nutrients brought to the surface layers by the upwellings
at the Antarctic Convergence.

Animals
need to have a whole range of specializations to be able
to take advantage of these conditions, those given here
are those that are most relevant to living in Antarctica,
there are many other adaptations of these animals.

Anatomical - Structures of
the body.

Behavioural - The manner in
which animals move and act.

Physiological - The functioning
of the animal at levels from biochemical, to cellular,
tissue, organ and whole organism levels.

Largest of all penguins
by a considerable margin. Animals of the very deep south
and the only large animal that remains in Antarctica
in the depths of the long dark winter night.

Large size retains heat - Emperors are twice the size
of the next biggest penguin, the king, so are able
to survive the winter fast and the extreme cold temperatures
endured at this time

Short stiff tail helps balance on land, forms a
tripod with heels on ice to give the least contact area
to prevent heat loss

Chicks have soft down for insulation, this is a
more effective insulator on land than the parents feathers,
but of little use in the sea, they must moult before
they can swim

Highly specialized bird skeleton a highly upright
gait, short neck, short legs and long body

Powerful claws on the feet help to gain a grip on
snow, ice or rock when emerging from the ocean or when
tobogganing

Huddle together in the winter to conserve heat,
without this they wouldn't be able to survive the
Antarctic winter

Unlike other penguin species, they are not aggressively
territorial, hence the huddling (above)

Breed during the depths of the Antarctic winter,
so the chicks are large enough to become independent
during the summer abundance of food

No nest is made, eggs then chicks sit on the parents
feet and covered by a fold of skin to keep them
warm

When the female lays her egg, it is passed over to the
male, the female then goes to sea and will not return
for an average of 115 days

A complex heat exchange system allows 80% of heat
in the breath to be recaptured in the nasal passages

They can dive to a depth of 1,800 feet (550 meters)
and hold their breath for up to 22 minutes, so are
able to reach and exploit food resources that other
birds can't reach

The normal resting heart-beat is about 60-70 beats
per minute (bpm), this goes up to 180-200 bpm before
a dive as they load up with oxygen, as they hit the
water, the rate drops to 100 bpm immediately slowing
to 20 bpm for most of the dive

Males can make "milk" in the oesophagus
which can be used to feed chicks in the winter before
the female arrives back from fishing

A Crustacean member of
the zooplankton, krill is a super-abundant organism
about 4-5cm long that feeds on phytoplankton. Being
unusually large for zooplankton they are eaten by just
about anything and everything that comes across them

Very fine filtering net or "basket" formed
by 6-8 pairs of limbs that can capture phytoplankton
down to 1Ám (1 micrometer, a millionth of a meter),
the smallest that there are, no other zooplankton
of this size can do this

Small bioluminescent organs are found on several
places on a krill's body, they have a reflector at the
back, a lens at the front and can be directed using
muscles, the function is not fully known, it may be
connected with schooling or mating. For this
reason krill are sometimes called "light shrimp"

Complex and highly developed compound eyes, one
of the best visual structures in nature, though why
this should be so in krill is a mystery

Swarming behaviour similar to schools of small fish
as a defence against predators, such swarms can have
up to 10,000 to 30,000 individuals per cubic meter of
sea water

In the winter and spring they are found beneath sea
ice where they feed on algae growing on the under
side of the ice which they rake off in a methodical
manner like a lawn mower

Rapid backwards escape reaction in common with many
other crustaceans with a pronounced flattened tail or
telson, they can flip it backwards several times in
succession to escape from danger - this is called "lobstering",
you can probably guess why.

Usually krill stay in deep water during daylight hours
and come to the surface at night, this helps them
to avoid predators

Can withstand long periods of starvation (up to 200
days) by using their muscle as a reserve, the krill
shrink in the process, this happens over the winter
months when the krill are under seasonal sea ice and
there is little or no photosynthesis

Despite very cold water temperatures, krill are highly
active, backwards lobstering takes only 55 milliseconds
(0.055s) from stimulus (optical) to triggering of the escape
response

Female Antarctic krill can lay up to 10,000 eggs at
a time, they can do this several times in a season

The largest animal ever to have lived, larger
than any dinosaur its huge bulk being supported by
the sea. Not exclusively an Antarctic animal, the
Antarctic subspecies B. m. intermedia
is the largest of three subspecies. They can eat up
to 4 tonnes of food a day in the Antarctic summer,
they feed for about 8 months and then fast for 4
months living off their fat reserves.

Baleen plates in the mouth instead of teeth.
These are made of keratin, the same tough protein
that makes hair and nails. They hang down from the
upper jaw forming the two uprights of a triangle
with the lower jaw being the flat third side. The
bristly edges
are filters to collect the krill in the water they
gulp in before swallowing them when the excess water
has been ejected.

55 - 68 ventral grooves that extend from the lower
jaw to the navel. These allow a huge mouthful
of water and food to be taken, expanding to about 6
times larger than normal size, the water is pushed
out by the enormous tongue and food filtered out by
the baleen plates.

A ridge in front of the blowholes (the two nostrils)
which are located on top of the head. Pointing
backwards means that they are not filled with water
when swimming and being placed on top of the head
makes it easy to breathe while lifting and exposing
the smallest amount of the body possible.

Huge tail fin the size of two dinner tables that
provide the propulsion for swimming. The smaller
forward fins are for changing direction and the
small dorsal (mid-back) fin helps with stabilizing
straight swimming.

Blue whales migrate to polar regions during the
summer months of that region. There are
distinct southern and northern populations which go
to their respective pole, none go to both poles.
They feed continuously during the super-productive
summer months and then live entirely on their
blubber reserves for about 4 months during the
breeding season in warmer waters. Not all
individuals migrate however.

Blue whales use sound to communicate with each other
and also possibly as a means of finding krill
swarms. They have been described as making the
loudest noise made by any animal at 180 dB or more.
These sounds can travel underwater for as far as 500
miles (800 km). They are very low frequency sounds
down to 14hz, below the hearing limit of humans.

Usually found alone or in small groups of 2-4
individuals though occasionally and rarely in larger
groups of up to 60 have been reported.

Adult blue whales have a daily energy requirement in
the region of 6.3 million Kilojoules (1.5
million kilocalories). This is supplied by up to 3.6
tonnes or 40 million individual krill eaten per day
which all have to be processed by the digestive
system.

Like many other air breathing diving animals such as
other whales, seals, and penguins, blue whales have
muscles rich in myoglobin. This is an iron
containing protein similar to haemoglobin that
carries oxygen in the blood, but provides an extra
in-situ store for longer dives exactly where it is
needed.

Metabolism is able to cope with extended periods of
plenty where extensive feeding allows the build up
of many tonnes of blubber (stored fat) which is
then used up during extended periods of starvation.